1. Field of the Invention
The invention relates to vehicle seat. More particularly, the invention relates to a vehicle seat in which a seating surface of a seat cushion or a seatback is formed with a pleat structure.
2. Description of Related Art
When a cover of a seat cushion or a seatback that forms a vehicle seat is made of leather material, a seating surface is often attached by a pleat structure. When the seating surface is formed with a pleat structure, pad block portions that are divided by this pleat structure are formed as convex shapes. Therefore, the overall shape of the seating surface is formed by a plurality of convex pad block portions that are fit together. Also, regardless of whether the seating surface is a seat cushion or a seatback, the center portion position is a flat surface, with so-called side portions that are positioned on both sides in the width direction shaped protruding toward a seated person, such that the overall shape of the seating surface is a concave shape. As a result, seating performance such as so-called holding performance of the seated person to the seating surface is able to be ensured. With a seat cushion, the protruding shape of the side portions toward the seated person, which makes the overall seating surface a convex shape, is a shape that rises up from a top surface at a middle position as shown by the broken line in FIG. 6. Also, this rising position on both sides is a position that enables the top surface to be formed relatively wide, taking into account differences in body shapes, e.g., physical builds, of seated people. As a result, the vehicle seat is able to be applied to a seated person of average build. The protruding side portions are formed with hard pads to receive the body as it rolls when lateral acceleration is applied to the seated person.
However, with a seating surface in which the concave-shaped top surface of the seating surface is formed wide and the side portions on both sides are positioned relatively far apart from each other as described above, the shape of the buttocks (i.e., the rear) of the seated person does not match the position of joining portions where the side portions and the flat top portion join together, and as a result, a gap is created therebetween. Therefore, the buttocks of the seated person tend not to be well-received by the overall seating surface (i.e., the overall seating surface tends not to fit the buttocks of the seated person well), and as a result, the so-called seating comfort is poor. Also, with a structure of a seating surface such as that described above, a gap is created on both sides of a seated person having a narrow build, so the holding performance may deteriorate. Forming the side portions closer together on both sides would solve this problem for a person having a narrow build, but would conversely make it more difficult to seat a wider person, so the seating comfort (i.e., the fit) and the holding performance may both be poor. Thus, in this way, it has been difficult to obtain good seating performance such as holding performance and seating comfort for people of different body shapes, e.g., physical builds.